Fractals are geometric shapes that exhibit self-similarity and complex patterns that are repeated at different scales. They can be used to describe irregular shapes found in nature, such as trees, coastlines, and clouds. The document discusses how Benoit Mandelbrot introduced fractals and developed their theory. It provides examples of famous fractals like the Mandelbrot set and Julia set and explains how fractals appear throughout nature and can be modeled using computers. Fractals have applications in fields like mathematics, science, engineering, art and music.